April 2, 2009

Overuse Of CT Scans Risky Business

CT scans are great at helping doctors determine what's wrong. But too many of these scans might be promoting illness rather than helping to diagnose it.

According to Boston researchers, having too many CT scans raises the risk of radiation-induced cancer.

The investigators arrived at that conclusion after looking at more than 31,000 patients who underwent more than 190,000 CT scans over a 22-year period. Among the group, 33 percent had five or more scans. Five percent had more than 22 of the exams, and 1 percent had more than 38.

Using a statistical model, the researchers determined about 7 percent of the total group had a 1 percent increase in lifetime risk of getting cancer due to excessive CT scans. Those exposed to the greatest number of scans saw an increase of as much as 12 percent.

Why do CT scans increase the risk? The researchers note these scans deliver considerably more radiation than other imaging tests. For example, 15 percent of the population studied received cumulative radiation doses of more than 100 millisieverts "“ about the same as one would receive from 1,000 chest x-rays.

"CT is an excellent diagnostic tool of tremendous clinical value in many situations," study author Aaron Sodickson, M.D., Ph.D., was quoted as saying. "Individual decisions about its use should balance the expected clinical benefits against the potential cumulative risks of recurrent imaging."